[Campbell Biology P.312] Observing the diagrams, how does the alignment of chromosomes at th... | Practice Question

Observing the diagrams, how does the alignment of chromosomes at the metaphase plate in Mitosis lead to genetically identical daughter cells, while the alignment in Meiosis I leads to variation?

  • A: In mitosis, individual chromosomes align, so sister chromatids separate, giving each daughter cell an identical full set. In meiosis I, homologous pairs align, and their separation is random, creating different combinations of parental chromosomes in daughter cells.
  • B: In mitosis, homologous pairs align, leading to identical cells. In meiosis I, individual chromosomes align, leading to variation.
  • C: The variation in meiosis is caused by crossing over, not by the alignment of chromosomes at the metaphase plate.
  • D: Both processes lead to genetic variation, but meiosis produces more.

Explanation

In mitosis, every chromosome aligns individually. When sister chromatids separate, each new cell gets an identical copy of every chromosome. In Meiosis I, homologous pairs one maternal, one paternal align. The orientation of the paternal vs. maternal chromosome to a given pole is random for each pair. This 'independent assortment' creates new combinations of parental chromosomes in the daughter cells of meiosis I, which is a major source of genetic variation.